Welding materials and processes



INVENI'OR.

CHARLES A.CADWELL ATTORNEYS Oct. 30, 1945.

c. A. CADWELL WELDING MATERIALS AND PROCESSES Filed Aug. 8, 1942 Patented Oct. 30, 1945 WELDING MATERIALS AND PROCESSES Charles A. iadwell, Cleveland Heights, Ohio, as-

- signor to The Electric Railway Improvement Company, Cleveland, Ohio, a corporation of hio Application August 8, 1942, Serial No. 454,189

26 Claims.

The present improvements, relating as indicated to welding, and having more particular regard to a method of welding in which the molten metal employed in the operation, is produced by the exothermic reaction between a metallic oxide and a strong reducing agent such 'inherent in the production of molten metallic copper by an exothermic reaction between copper oxide and aluminum and disclose a method and composition of materials whereby such reaction, generally known as the Thermit process.

may be utilized, despite the great speed with which the reaction takes place and the excessive heat evolved. Briefly stated, such previously disclosed improvement resides in the use instead of aluminum by itself of sufficient copper as metal (preferably in the form of an alloy) with the aluminum to absorb a substantial amount of the heat generated by the reaction. At the same time there is obtained an increased amount of mopper made up of that produced by reduction of the oxide plus the copper present as such in the mixture.

Molten copper produced by use of the material and in the manner set forth in my previous patent has been found highly satisfactory for use in welding copper bonds to steel rails. However, particularly where a charge or "shot of molten copper is required in small amount only, as for example in welding small size, e. g. signal, bonds to rails by exothermic reaction, it is still difficult accurately to control the speed of such exothermic reaction and avoid a spattering of molten metal. It has also been found that due to the rapid chilling where a cold mold is employed there is a tendency for the weld metal to solidify in other than desired solid form but to assume a 'pufiy" condition. While the reason for this last-mentionedbehavior has not been firmly proven, it has heretofore been found desirable to heat the mold in order to avoid it.

I have now discovered that the temperature of molten metal produced by exothermic reaction between a metallic oxide and a strong reducing agent, such as aluminum, can be regulated and the behavior and condition of such molten metal otherwise greatly improved by including in the mixture a suincient amount of another metal less avid for oxygen than aluminum, e. g. iron.

With the object accordingly of providing a method oi producing molten metal by exothermic reaction, whether for welding or'other purposes, in such a manner and at a temperature regulated according to the purpose for which the metal is to be used, my present invention consists of the steps and composition of ingredients comprising the exothermic reaction mixture hereinafter fully described and particularly pointed out in the claims, the annexed drawing and the following description setting out in detail certain means and one mode of'carrying out such invention, such disclosed means and mode illustrating, however, but one of the various ways in which the principle of the invention may be used.

In said annexed drawing:

Fig. 1 is a cross sectional view of a cartridge wherein my improved exothermic reaction mixture is conveniently placed preparatory to use in a welding operation; and

Fig. 2 is a side elevational view, partly in cross section, indicating the manner in which the crucible of a rail bonding apparatus may be charged with such mixture.

As set forth in my previous Patent No. 2,229,- 045, a charge found satisfactory for use in welding copperrail bonds to rails co p ises as its principal ingredients approximately 14.4 parts by weight of roasted copper scale to 5.6 parts of -35 Cu-Al alloy, all being finely divided and thoroughly mixed. If the parts comprising such mixture be taken as grams, such charge will give a theoretical yield of copper of something over 16 grams. Of such resulting copper a portion is of course derived from the reducing action of the aluminum on the copper oxide in the copper scale, in accordance with the following reaction, v1z.:

The balance is made up of the copper which is found in such scale and of the 65% of copper included in the copper-aluminum alloy. The copper from thetwo last mentioned sources serves not only thus to furnish additional metal. Y

scale and Al-Fe alloy.

minum and copper oxide to produce highly heated molten copper, instead of utilizing copper metal as such, either alloyed with the aluminum or found in association with copper oxide in the copper scale used, there is included in the charge a certain amount of metallic iron or equivalent metal which at the high temperatures involved will likewise abstract oxygen from such copper oxide. For the production of molten copper in small amounts suitable for use in a welding operation such as the attachment of a copper bond to a steel rail, I have found the following proportions of ingredients satisfactory, viz., copper scale approximately 80%, aluminum approximately 10% and iron approximately 10%, where such scale is composed approximately of copper oxide, the balance being unoxidized copper at the center of the granules. The aluminum and iron employed in the charge will preferably be a 50-50 alloy of the two metals, although an intermixture thereof in finely ground form may be used. The 50-50 Al-Fe alloy however is preferable because of the ensured thorough and uniform mixture of the two metals, and further Parts by weight Copper scale 19 Al-Fe alloy (50-50) 5 Total 24 In the foregoing example the copper oxide is assumed to have the following composition, viz.:

- g Parts by weight Copper oxide (CuO) 12.92 Unoxidized copper 6.08

The parts by weight ofthe principal ingredients composing the charge will of course vary slightly depending upon the composition of the particular copper scale employed, the latter, as is well known, being a mixture of cuprous oxide, C1120, and cupric oxide, CuO, with more or less unoxidized copper, depending upon the stage of oxidation of the material.

In addition to theabove described principal ingredients the charge will also desirably include a small amount (approximately 2%) each of silicon carbide (carborundum) and manganese boride, these additional ingredients being of course thoroughly intermixed with the copper In the example given above the corresponding parts by weight of such silicon carbide and manganese boride will be 1/2. Although this will vary, particularly in the case of the boride, depending upon whether the latter is in the form-of the monoor dicompound.

In the above typical composition given by way of example, the 2% parts of aluminum will-require for reaction only 11 parts of the approximately 13 parts of copper oxide in the scale, the balance of such copper. oxide being reduced by the 2 parts of iron with the evolution of more heat. As comparedwith the typical charge described in my issued patent, there will be more heatdeveloped owing to the larger aluminum content to which will be added that resulting from the reaction of the iron. Nevertheless, tests have indicated that the new composition is slower in action than the composition thus formerly employed, does not spatter, andthat the resulting molten copper when shot into a cold mold does not puii. The manganese added through the manganese boride has of course less aiilnity for oxygen than the aluminum or iron placed in a cylindrical cardboard container 9, one v end 2 of which constitutes a removable cap. In filling such cartridge a small amount of a starting or igniting powder, as describedin my Patent No. 2,229,045, is desirably first placed therein so that when the cartridge is emptied into a crucible or mold'5 (see Fig. 2 of the drawing) such starting powder will be found at the top of the depositedmixture. The rail bonding apparatus illustrated in Fig. 2, it will be understood, forms no part of the present invention. Briefly stated, it comprises in addition to the mold 5 a suitable clamping mechanism 6 whereby the mold may be clamped against the 'rail head '7, such mold having a cavity 8 in which the molten metal resultingfrom the exothermic reaction is received. The terminal of bond 9- molten copper drops into the cavity of the mold and surrounds the bond terminal. By utilizing a mixture of the ingredients for the charge as just described, in properly regulated proportions,

such bond terminal is interfused with the charge and the adjacent face of the rail heated to the proper temperature so that the bond is firmly attached to the rail, all without spatter or loss of metal. The operation is extremely expeditious and the resulting bond head is uniformly sound, i. e. llOl'lr-DOI'OUS or iiufiy.

Other modes of applying the principle of my invention may be employed instead of the one explained, chang being made as regards the process herein disclosed or the materials employed in carrying out the process, provided the step. or steps stated by any of the following claims or the equivalent of such stated step or steps be employed.

I therefore particularly point out and distinct ly claim as my invention:

1. In the production of metal having a lower melting point than iron by the exothermic reaction between an oxide of such metal and aluminum, the step'which comprises including in the reaction mixture sufllcient metallic iron to reduce a substantial part of such oxide.

2. In a method of welding in which molten metal produced by the exothermic reaction of copper oxide and aluminum is employed as a welding agent, the step which comprises including suflicient metallic iron in the reaction mixture to reduce a substantial partof the copper oxide. I

ing metallic iron in the reaction mixture in 1 amount substantially equal to the aluminum.

4. In a method of welding in which molten metal produced by the exothermic reaction of copper oxide and aluminum is employed as a weldingxagent, the step of regulating the temperature of such molten metal whichcomprises including suflicient metallic iron in the reaction mixture to reduc a substantial part of the copper oxide, such iron being alloyed with the aluminum employed.

5. In a method of welding in which molten metal produced by the exothermic reaction of copper oxide and aluminum is employed as a welding agent, the step of regulating the temperature of such molten metal which comprises including sufficient metallic iron in the reaction mixture toreduce a substantial part of the copper oxide, such iron being alloyed with the aluminum employed in approximately equal amounts.

6. A composition of matter for use in a metalproducing exothermic reaction, where the desired metal has a lower melting point than iron. comprising amixture of an oxide of such metal, metallic aluminum and suflicient metallic iron to reduce a substantial part of such oxide.

7. Composition of matter for use in a metal producing exothermic reaction comprising a mixture of'copper oxide and aluminum, and sumcient iron incorporated in said mixture to reduce a substantial part of the copper oxide.

8. Composition of matter for use in a metal producing exothermic reaction comprising a mixture of copper oxide and aluminum, and sumcient iron incorporated in said mixture to reduce a substantial part of the copper oxide, such iron being alloyed with the aluminum.

9. Composition of matter for use in a metal producing exothermic reaction comprising a mixture of copper oxide and aluminum, and sumcient iron incorporated in said mixture to reduce a substantial part of copper oxide, such iron being alloyed with the aluminum in approximately equal amounts.-

10. Composition of matter for use in a metal producing exothermic reaction comprising a mixture of approximately 80% of copper oxide and 20% of aluminum and iron.

11. Composition of matter for use in a metal producing exothermic reaction comprising a mixture of approximately 80% of copper oxide and 20% of aluminum and iron, such aluminum and iron being in approximately equal amounts.

12. Composition of matter for use in a metal producing exothermic reaction comprising a mixture of approximately 80% of copper oxide and 20% of aluminum and iron, such aluminum and iron being in the form of an alloy.

13. Composition 0! matter for use in a metal producing exothermic reaction comprising a mixture of approximately 80% of copper oxide and 20% of aluminum and iron, such aluminum and iron being in the form of an alloy composed '0! approximately equal amounts of the two metals.

14. Composition of matter for use in a metal producing exothermic reaction comprising a mixture of copper oxide and aluminum, sufflcient iron incorporated in said mixture to reduce a substantial part of the copper oxide, and a small percentage of silicon carbide.

15. Composition of matterfor use in a metal producing exothermic reaction comprising a mixture of copper oxide and aluminum, suflicient iron incorporated in said mixture to reduce a substantial part of the copper oxide, and a small perpercentage each of silicon carbide and manganese boride.

l7. Composition of matter for use in a metal producing'exothermic reaction comprising a mix ture of approximately of copper oxide and 20% of aluminum and iron, such aluminum and iron being in approximately equal amounts, to-

gether with a small percentage of silicon carbide;

18. Composition of matter for use in a metal producing exothermic reaction comprising a mixture of approximately 80% of copper oxide and 20% of aluminum and iron, such aluminum and iron being in approximatehv equal amounts, together with a small percentage of manganeseboride.

19. Composition of matter for use in a metal producing exothermic reaction comprising a mixture of approximately 80% of copper oxide and 20% of aluminum and iron, such aluminum and iron being in approximately equal. amounts, together with a small percentage of each of silicon carbide and manganese boride.

20. Composition of matter for use in a metal producing exothermic reaction comprising a mixture of approximately 80% of copper oxide and 20% or aluminum and iron. such aluminum and iron being in the form of an alloy composed of approximately equal amounts 0! the two metals, said mixture also including approximately 2% each of silicon carbide and manganese boride.

'21. In a method of welding in which molten metal produced by the exothermic reaction of copper oxide and aluminum is employed as a 22. In a method or welding in which molten metal produced by the exothermic reaction of copper oxide and aluminum is employed as a welding agent, the step which comprises including a small percentage of manganese boride.

23. In amethod of welding in which molten metal produced by the exothermic reaction or copper oxide and aluminum is employed as a welding agent, the step which comprises including a small percentage each of, silicon carbide and manganese boride.

24. A composition 01' matter for use in a metal producing exothermic reaction comprising a mixture of copper oxide and a metallic element capable of reducing such oxide. together with a small percentage of silicon carbide.

25. A composition of matter for use in a metal producing exothermic reaction comprising a mixture of copper oxide and a metallic element capable' oi reducing such oxide, together with a small percentage of manganese boride.

26. A composition of matter for use in a metal producing exothermic reaction comprising a mixture of copper oxide and a metallic element ca-= pable of reducing such oxide, together with a manganese boride.

CHARLES A.- ,CADWELIJ. 

